Classification of meniscal tear is necessary only for partial resection. In western countries many reports said that medial meniscal tear is commoner than that of lateral meniscus. Actually the reverse is true in Korea and in some other oriental countries, However there is no plausible explanation concerning this matter. In this report 250 knees of 240 patients were involved. We performed arthroscopic meniscectomy in all cases and we investigated the relationship between the pattern of tear and many possibly related factors. The follow-up period was 1–8 years, the ratio of male-female was 163:77, and the range of age was varied between 7 and 71 tears with the young and middle age groups being predominant. Right and left side ratio was 117:113 and the involvement of both knees was noted in 20 knees of 10 patients. The results were as follows: 1. The medial menisci were torn in 100 knees and was less than 142 lateral meniscal tear, with the ratio being 1:1.4. The tear of lateral meniscus was commoner in the age group of less than 30 years and the tear of medial meniscus was commoner in the age group older than 50 years whereas there was no difference in the age group of inbetween. 2. The commonest pattern of tear was longitudinal one including peripheral tear, that is 135 knees (54.0%), followed by complex tear, 50 knees (20.0%), oblique tear, 40 knees (16.0%), horizontal tear, 21 knees (8.4%) and lastly superior and inferior flap tear, 5 knees (2.0%). 3. The longitudinal tear was most prevalent in the age group of 20–40, whereas the complex tear was most prevalent in the age group of beyond 50 years (p<0.05). 4. The longitudinal tear was significantly prevalent in lateral menisci, the complex tear in medial menisci (p<0.05), whereas the transverse and oblique tear were not significantly prevalent in either meniscus (p>0.05). 5. In the longitudinal tear group, the tear occured most frequently in the midsubstance of posterior portion in the medial menisci without statistical significance (p>0.05) wereas the tear occurred most frequently in the periphery of the anterior portion in case of lateral menisci (p<0.05). 6. There were 37 discoid lateral menisci, with the longitudinal tear being the commonest. 7. Ground sports injuries occurred only in 34 knees (13.6%), with the longitudinal tear being significantly commoner than in the other injuries. From these results it would be suggested that although the discoid lateral meniscus has to be given much weight in the total meniscal injuries another explanation should be given concerning the prevalence of lateral meniscus tear compared to the medial meniscus tear and the prevalence of longitudinal tear.